In our prior U.S. Pat. No. 4,502,816, we described the production of a shoreline breakwater produced from reinforced concrete prismatic modules having a gently sloping seaward face which were assemblable in side-by-side relation on the sea bottom to form an artificial reef. Tests over a three year period on the North Shore of Long Island in a location where shoreline erosion has caused severe property damage in recent years have demonstrated the patented device is indeed effective in preventing continued erosion and serves to capture sand in great quantities so as to build the beach without robbing sand from adjacent properties and thereby causing harm. It was found that individual modules comprising the breakwater moved in relation to adjoining modules resulting in an uneven contour to the overall reef, thereby creating esthetic concerns. It was accordingly deemed desirable to improve the stability of the artificial reef in contact with the powerful destructive forces of the sea so as to improve the esthetic appearance of the reef over time and also to improve the performance of the reef in capturing sand and protecting the shoreline. It is to these objectives that the present invention is directed.